gma500: do a pass over the FIXME tags
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/gma500/gtt.c b/drivers/gpu/drm/gma500/gtt.c
index 461ead2..a246239 100644
--- a/drivers/gpu/drm/gma500/gtt.c
+++ b/drivers/gpu/drm/gma500/gtt.c
@@ -72,9 +72,8 @@
* @r: our GTT range
*
* Take our preallocated GTT range and insert the GEM object into
- * the GTT.
- *
- * FIXME: gtt lock ?
+ * the GTT. This is protected via the gtt mutex which the caller
+ * must hold.
*/
static int psb_gtt_insert(struct drm_device *dev, struct gtt_range *r)
{
@@ -111,7 +110,8 @@
* @r: our GTT range
*
* Remove a preallocated GTT range from the GTT. Overwrite all the
- * page table entries with the dummy page
+ * page table entries with the dummy page. This is protected via the gtt
+ * mutex which the caller must hold.
*/
static void psb_gtt_remove(struct drm_device *dev, struct gtt_range *r)
@@ -136,7 +136,8 @@
* @gt: the gtt range
*
* Pin and build an in kernel list of the pages that back our GEM object.
- * While we hold this the pages cannot be swapped out
+ * While we hold this the pages cannot be swapped out. This is protected
+ * via the gtt mutex which the caller must hold.
*/
static int psb_gtt_attach_pages(struct gtt_range *gt)
{
@@ -158,7 +159,7 @@
gt->npage = pages;
for (i = 0; i < pages; i++) {
- /* FIXME: review flags later */
+ /* FIXME: needs updating as per mail from Hugh Dickins */
p = read_cache_page_gfp(mapping, i,
__GFP_COLD | GFP_KERNEL);
if (IS_ERR(p))
@@ -181,7 +182,8 @@
*
* Undo the effect of psb_gtt_attach_pages. At this point the pages
* must have been removed from the GTT as they could now be paged out
- * and move bus address.
+ * and move bus address. This is protected via the gtt mutex which the
+ * caller must hold.
*/
static void psb_gtt_detach_pages(struct gtt_range *gt)
{
@@ -390,15 +392,18 @@
pg->gtt_phys_start = dev_priv->pge_ctl & PAGE_MASK;
/*
- * FIXME: video mmu has hw bug to access 0x0D0000000,
- * then make gatt start at 0x0e000,0000
+ * The video mmu has a hw bug when accessing 0x0D0000000.
+ * Make gatt start at 0x0e000,0000. This doesn't actually
+ * matter for us but may do if the video acceleration ever
+ * gets opened up.
*/
pg->mmu_gatt_start = 0xE0000000;
pg->gtt_start = pci_resource_start(dev->pdev, PSB_GTT_RESOURCE);
gtt_pages = pci_resource_len(dev->pdev, PSB_GTT_RESOURCE)
>> PAGE_SHIFT;
- /* CDV workaround */
+ /* Some CDV firmware doesn't report this currently. In which case the
+ system has 64 gtt pages */
if (pg->gtt_start == 0 || gtt_pages == 0) {
dev_err(dev->dev, "GTT PCI BAR not initialized.\n");
gtt_pages = 64;
@@ -412,13 +417,16 @@
if (pg->gatt_pages == 0 || pg->gatt_start == 0) {
static struct resource fudge; /* Preferably peppermint */
-
/* This can occur on CDV SDV systems. Fudge it in this case.
We really don't care what imaginary space is being allocated
at this point */
dev_err(dev->dev, "GATT PCI BAR not initialized.\n");
pg->gatt_start = 0x40000000;
pg->gatt_pages = (128 * 1024 * 1024) >> PAGE_SHIFT;
+ /* This is a little confusing but in fact the GTT is providing
+ a view from the GPU into memory and not vice versa. As such
+ this is really allocating space that is not the same as the
+ CPU address space on CDV */
fudge.start = 0x40000000;
fudge.end = 0x40000000 + 128 * 1024 * 1024 - 1;
fudge.name = "fudge";